Apparatus for acetylene generation from hydrocarbons



July 13, 1954 S. P. ROBINSON APPARATUS FOR ACETYLENE GENERATION FROM HYDROCARBONS Original Filed Aug. 21, 1947 INVENTOR.

5AM P. ROBINSON A TTORNEYS atented July 13, 1954 UNITED STATES ATENT, OFFICE APPARATUS FOR ACETYLENE GENERATION FROM HYDROCARBONS Sam P. Robinson, Bartlesville, Gkla., assignor to Phillips Petroleum Company, a corporation of Delaware 4 Claims.

This invention relates to apparatus for the production of hydrocarbons high in carbon content, i. e., in weight per cent of carbon, from hydrocarbons low in carbon content by partial combustion with elemental oxygen or oxygenrich streams, and more particularly to apparatus for the production of acetylene from parafiin and olefin hydrocarbons, and to apparatus for producing high yields thereof. This application is a division of my copending application Serial No.

769,795, filed August 21, 1947, now Patent No. 2,561,996, granted July 24, 1951.

t is known in the art that hydrocarbons may be cracked by partial combustion of low-carbon hydrocarbons with air, but the diluent effect of the nitrogen causes low thermal eificiencies. It has also been proposed to preheat oxygen and hydrocarbons separately and to mix them in a reaction chamber to dehydrogenate the hydro carbons at a fixed elevated temperature. The prior methods and apparatus for production of the higher carbon hydrocarbons, for example, acetylene, have been effective for concentrations from 3% up to, in some cases 10% by volume, but higher percentages have not been attained and impurities have been formed which are difiicult of removal.

Among the objects of the present invention are to provide apparatus for the continuous production of high-carbon hydrocarbons in high concentration, for example, in excess of 20% of the volume of the initial hydrocarbon; more efficient operation of the required apparatus; independent heating means for the hydrocarbon and the oxygen, and a cooperative relationship between the various zones of the hydrocarbon reaction chamber or chambers and the oxygen heating apparatus. Further advantages of the invention are successively more rapid reaction times as the reaction progresses, successive in- I troduction of oxygen at higher temperatures, decreased partial pressures of the reaction hydrocarbon at successive stages in the reaction, and automatic introduction of oxygen at progressively higher temperatures at intermediate progressive stages of the reaction cycle.

While the invention is particularly adapted to the production of acetylene from paraffin hydrocarbons such as ethane, it is to be understood that other hydrocarbons may be used as the starting materials or as intermediates, including olefins such as ethylene. It is also to be understood that the invention is applicable to the production of olefins from parafiins; for example, ethylene, from ethane; although the most advantageous use of the invention at present, for economic reasons, is in the manufacture of acetylene on a commercial basis at extremely low cost.

In practicing the invention, ethane is first preheated by suitable means and introduced, together with free oxygen which has also been preheated, into a reaction chamber containing small pebbles of aluminum oxide which effect thorough dispersion and mixture of the ethane and the oxygen. Each of the reaction chambers contains a fixed bed of refractory pebbles. It is preferred that the ethane be heated to between 1000 and 1500 F. prior to introduction into the first reaction chamber, and that the oxygen be preheated to a temperature within the range of 700 to 1000 F. The effluent from the first reaction chamber, which comprises relatively high concentration of ethylene is then mixed with additional oxygen which has been preheated to a higher temperature than the initial oxygen, for example from 1000 to 1500 F. The mixture containing the additional increment of preheated oxygen is then introduced into a second reaction chamber and partial combustion takes place at a higher temperature, for example 2000 to 2500 F. and for a shorter period of time than the initial reaction. The reaction in the first chamber may occur in 0.5 second at a temperature between 1500 F. and 2000 F., vhereas the reaction in the second chamber may occur in a period of time which is about one-fifth that of the first, e. g., 0.10 second. The reaction may be caused to progress in one or more subsequent reaction chambers by the introduction of additional oxygen heated to an even higher temperature, for example, 2000 F. to 2500 F. This additional increment of oxygen may be mixed with the effluent in a mixing bustle and the admixture introduced into an even smaller reaction chamber having a temperature in excess of 2500 F., this reaction taking place in a considerably reduced period of time, of the order of 0.02 second. Further reaction stages may be carried out, if desired, but it has been found that the concentration of acetylene thus produced from ethane in the efiluent of the third reaction chamber is in excess of 20% by volume.

The final efiluent containing the acetylene in high concentration is then cooled, for example, by a quenching spray of water or other quenching medium, to a temperature at which the acetylene may be recovered without further reaction, and the impurities are removed in conventional manner.

While any desired heating means may be used for progressively raising the temperature with the increments of oxygen, it has been found highly desirable and economical to provide a heating chamber, or preferably a series of heating chambers through which the oxygen is passed in the direction of the source of heat. The source of heat is preferably a continuously travel= ling quantity of heating elements which pass through the oxygen heater-or series of heaters countercurrently to the flow of oxygentherethrough. It has been found convenient to userefractory pebbles as the heating elements and to pass them downwardly through a vertically arranged series of heating chambers while passing the oxygen upwardly throughtheychambers, thereby providing the highest temperatures for the oxygen in the uppermost heating temperature and the lowest temperatures at the bottom of the stack, the intermediate volumes of oxygen being progressiyelyjhotter as the oxygen is. forced upward. When this arrangement is used for the heater,.it is particularly convenient to similarly stack the reaction chambers with the first and largest volume chamber at the lowermostposition and the last and smallest chambar at theuppermost position. In accordance with'this inventionit is preferred to arrange the oxygen heating chambers opposite the respective reaction chambers to which the oxygen at the various temperatures is to be introduced, thereby avoiding heat losses and excessive lengths of the conduits leading. from the heaters to the reaction chambers.

Referring to the drawing, which is a diagrammaticrepresentation, the'hydrocarbon is preheated by introducing gaseous or liquid fuel and air through the conduit into a mixing chamber 2 .andthence through conduit 3 into a preheater 4. Hydrocarbon is introduced at 5 through a coil 6 within the preheater and thence through conduit I to a hydrocarbon distributor 8.. While a specific method and apparatus are described for the preheating of the hydrocarbon, itis of course understood that any other suitable means may be used. The preheated hydrocarbon is then fed or forced into a mixing bustle 9. togetherzwith preheated oxygen from conduit l9 into the first reaction chamber ll wherein thermal pyrolysis causes partial dehydrogenation of the hydrocarbon, such as ethane, thereby effecting a high yield of ethylene. The effluent gases from chamber If at elevated temperature are mixed in a second mixing bustle 12 with oxygen introduced at the conduit 13 at higher temperature than the oxygen from conduit Ill. The mixture is then forced into a smaller reaction chamber l4 heated to a higher temperature than chamber ll, wherein the reaction takes place in a shorter time and the effiuent is mixed in a third mixing bustle IS with still hotter oxygen introduced from conduit 16. The mixture from the bustle it then passes into a still smaller reaction chamber l1, wherein further partial combustion takes place at a higher temperature than either of the two preceding reactions. The efliuent from the reaction chamber i! has a hi h acetylene content, i. a, over 20% by volume, and is withdrawn through conduit l8, and quenched by a fluid from conduit 19 such as a direct spray of water or other quenching medium, whence it emerges at 23.

As the gases pass from the first to the last reaction chamber, the partial combustion takes place at increasingly higher temperatures in the at successively higher temperatures.

presence of increasing amounts of hydrogen, steam and carbon oxides which effectively depress the partial pressure of the hydrocarbon reactant to insure higher yields of acetylene. The higher yields are also assisted by the decreasing size of the successive reaction chambers, as well as by the decreasing periods of time for the successive reactions. It is of course desirable to insulate the elements of the entire system including the conduits.

Atthe same time that the reaction is progressing, oxygen'introduced at conduit 2! is forced through aseries of heating chambers 22 and 23 The heating is effected by first introducing refractory pebbles through the conduit or chute 2 into a pebble heating chamber 25 which may be heated by introducing fluid fuel and air through conduit 25. After the pebbles are heated they descend from the heatingchamber 25 through a conduit 2's into chamber 23, where they are partially cooled by the influx of oxygen therethrough, and thence through conduit 28 into chamber 22 to heat the initial oxygen to a relatively lower temperature. The pebbles are removed through conduit 29 from the bottom of chamber 22 and are mechanically reintroduced along the path 35 back up to the chute 24 and into the heating chamber 25 to recommence another heating cycle. The stack gases from combustion of the fuel in chamber 25 are vented at conduit 3 l The lowertemperature oxygen is Withdrawn from chamber 22 'throughconduit 32 and is branched into conduits l6 and I3. A portion of the preheated oxygen from conduit 32 is mixed with highertemperature oxygen from conduit 33, thus yieldan oxygen feed at Iiiof intermediate temperature. The hottest oxygen, from conduit 33, is in part introduced into the mixing bustle 15 through conduit I8.

The conduits leading from the oxygen heating chambers to the mixers for the reaction chambers are preferably arranged in straight lines in order to reduce heat losses which would be occasioned by circuitous paths.

While a vertical arrangement is shown in the drawing for the heating chambers and the reaction chambers, and a gravity flow system for the heating elements is shown for the heating pebbles, it is to be understood that other arrangements may be employed without sacrificing the advantages of the invention.

As a specific example of practicing the invention, three parts by volume of ethane are preheated to l20 l-F. and then mixed in a bustle 9 with one part of oxygen heated to 800 F. from heater '22; The resulting mixture is then passed through afixed pebble bed in the reaction chamaer i l maintained at 1650 F. by partial combustion of part of the, ethane and cracked products. The efilucnt contains in excess of 36% by volume of ethylene and is then further cracked successivcly in the reaction chambers I l and H at increasing temperatures, in reduced reaction times and in the presence of increasing partial pressures, of hydrogen, steam, and carbon monoxide by incremental additions of increasingly hot oxygen from the conduits l3 and i6. Reaction times in the successive chambers are 0.5 second, 0.1 second, and 0.02 second, and the respective temperatures at which the pebbles in each of the reaction chambers are maintained are 1500-2006" F., 2090-2560 F., and about 26OG F. The respective temperatures for the oxygen introduced through conduits 58,. I3, and It are approximately 800 F., 1250 F., and 2000 F. The acetylene emerging from the conduit 18 at the top of the stack of reaction chambers is in volumetric concentration in excess of 20%. The efiiuent including acetylene, steam, and carbon oxides is then quenched down to a safe temperature and the impurities are removed in conventional manner.

In view of the many changes and modifications that may be made without departing from the principles underlying the invention, reference should be made to the appended claims for an understanding of the scope of the protection afforded the invention.

What is claimed is:

1. Apparatus for dehydrogenating a hydrocarbon comprising a first closed, fixed bed reaction vessel; a product outlet in the upper end thereof; a second closed fixed be reaction vessel located below said first vessel; a first conduit connecting the lower end portion of said first vessel and the upper end portion of said second vessel; a third closed, fixed bed reaction vessel located below said second vessel; a second conduit connecting the lower end portion of said second vessel and the upper end portion of said third vessel; a third conduit communicating with the lower end portion of said third vessel; heated gas supply means positioned in proximity to said reaction vessels; said heated gas supply means comprising a fourth closed vessel, a fifth closed vessel located below said fourth vessel, a pebble conduit connecting the lower end portion of said fourth vessel and the upper end portion of said fifth vessel, a sixth closedvessel located below said fifth vessel, a pebble conduit connecting the lower end portion of said fifth vessel and the upper end portion of said sixth vessel, an elevator connected to the lower end portion of said sixth vessel and the upper end portion of said fourth vessel, a feed conduit connected to the lower end portion of said fourth vessel, a gaseous efiiuent conduit extending from the upper end of said fourth vessel; a feed conduit extending into the lower end portion of said sixth vessel; a fourth conduit conmeeting the upper end portion of said sixth vessel, the lower end portion of said third vessel, and the lower end portion of said fifth vessel; a fifth conduit connecting the upper end portion of said fifth vessel and the lower end portion of said second vessel, a sixth conduit connecting the upper end portion of said fifth vessel and the lower end portion of said first vessel, and a seventh conduit connecting said fourth and fifth conduits.

2. The apparatus of claim 1 in which a preheater is located in said third conduit.

3. The apparatus of claim 1 in which said first, second, and third closed vessels are of increasing size, respectively.

4. The apparatus of claim 1 wherein the fixed bed in said first, second, and third reaction vessels consists of refractory particles.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,380,767 Welty Sept. 28, 1943 2,337,419 Sensel Dec. 21, 1943 2,398,185 Loy Apr. 9, 1946 2,432,872 Ferro, Jr. Dec. 16, 1947 2,458,359 Evans Jan. 4, 1949 2,458,487 Crowley, Jr. Jan. 4, 1949 2,518,688 Hasche Aug. 15, 1950 2,561,996 Robinson July 24, 1951 

1. APPARATUS FOR DEHYDROGENATING A HYDROCARBON COMPRISING A FIRST CLOSED, FIXED BED REACTION VESSEL; A PRODUCT OUTLET IN THE UPPER END THEREOF; A SECOND CLOSED FIXED BED REACTION VESSEL LOCATED BELOW SAID FIRST VESSEL; A FIRST CONDUIT CONNECTING THE LOWER END PORTION OF SAID FIRST VESSEL AND THE UPPER END PORTION OF SAID SECOND VESSEL; A THIRD CLOSED, FIXED BED REACTION VESSEL LOCATED BELOW SAID SECOND VESSEL; A SECOND CONDUIT CONNNECTING THE LOWER END PORTION OF SAID SECOND VESSEL AND THE UPPER END PORTION OF SAID THIRD VESSEL; A THIRD CONDUIT COMMUNICATING WITH THE LOWER END PORTION OF SAID THIRD VESSEL; HEATING GAS SUPPLY MEANS POSITIONED IN PROXIMITY TO SAID REACTION VESSELS; SAID HEATED GAS SUPPLY MEANS COMPRISING A FOURTH CLOSED VESSEL, A FIFTH CLOSED VESSEL LOCATED BELOW SAID FOURTH VESSEL, A PEBBLE CONDUIT CONNECTING THE LOWER END PORTION OF SAID FOURTH VESSEL AND THE UPPER END PORTION OF SAID FIFTH VESSEL, A SIXTH CLOSED VESSEL LOCATED BELOW SAID FIFTH VESSEL, A PEBBLE CONDUIT CONNECTING THE LOWER END PORTION OF SAID FIFTH VESSEL AND THE UPPER END PORTION OF SAID SIXTH VESSEL, AN ELEVATOR CONNECTED TO THE LOWER END PORTION OF SAID SIXTH VESSEL AND THE UPPER END PORTION OF SAID FOURTH VESSEL, A FEED CONDUIT CONNECTED TO THE LOWER END PORTION OF SAID FOURTH VESSEL, A GASEOUS EFFLUENT CONDUIT EXTENDING FROM THE UPPER END OF SAID FOURTH VESSEL; A FEED CONDUIT EXTENDING INTO THE LOWER END PORTION OF SAID SIXTH VESSEL; A FORTH CONDUIT CONNECTING THE UPPER END PORTION OF SAID SIXTH VESSEL, THE LOWER END PORTION OF SAID THIRD VESSEL, AND THE LOWER END PORTION OF SAID FIFTH VESSEL; A FIFTH CONDUIT CONNECTING THE UPPER END PORTION OF SAID FIFTH VESSEL AND THE LOWER END PORTION OF SAID SECOND VESSEL, A SIXTH CONDUIT CONNECTING THE UPPER END PORTION OF SAID FIFTH VESSEL AND THE LOWER END PORTION OF SAID FIRST VESSEL, AND A SEVENTH CONDUIT CONNECTING SAID FOURTH AND FIFTH CONDUITS. 